CN114593689B - Optical fiber end face detection method and device - Google Patents
Optical fiber end face detection method and device Download PDFInfo
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- CN114593689B CN114593689B CN202210227629.4A CN202210227629A CN114593689B CN 114593689 B CN114593689 B CN 114593689B CN 202210227629 A CN202210227629 A CN 202210227629A CN 114593689 B CN114593689 B CN 114593689B
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- 238000003384 imaging method Methods 0.000 claims abstract description 21
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Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/24—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B13/00—Optical objectives specially designed for the purposes specified below
- G02B13/22—Telecentric objectives or lens systems
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/0012—Optical design, e.g. procedures, algorithms, optimisation routines
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B3/00—Simple or compound lenses
- G02B3/02—Simple or compound lenses with non-spherical faces
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/005—Diaphragms
Abstract
The present disclosure relates to a method for detecting an end face of an optical fiber, wherein incident light from the end face of the optical fiber is converged by at least one lens, so that the end face of the optical fiber is imaged on an image plane; acquiring image information of the end face of the optical fiber based on imaging of the image plane, and measuring optical fiber parameters based on the image information; and blocking part of light rays on an image side focal plane formed by the at least one lens, so that the intersection point position of the object side chief ray in the light path tends to be infinity. The present disclosure also relates to an optical fiber end face measurement device. The method or the device has the characteristic of an object side telecentric optical system by partially blocking light rays in a focal plane. The imaging of the end face of the optical fiber is not affected by the change of the distance, and the shape and the size of the end face can be accurately obtained. The method has the advantage of clear edges, and can accurately lock the edges to obtain parameters of the fiber core. The super lens is preferably used, the volume is small, the convenient and quick measurement can be realized, and the low-cost advantage is realized.
Description
Technical Field
The application belongs to the field of production detection of optical fibers, and particularly relates to a method for detecting an end face of an optical fiber and a device suitable for the method.
Background
The design, drawing and end face detection of an optical fiber are closed loop processes, and particularly for special optical fibers, after a corresponding structure is designed, the manufacture and the subsequent drawing of an optical fiber preform are performed, and then the drawn optical fiber, particularly the end face shape, needs to be detected. The detection result can be fed back to engineers in real time in the process of drawing the optical fiber so as to adjust drawing parameters conveniently; and feedback can be provided for designers so as to facilitate the optimization design, error analysis and the like. The detection of the end face in the special optical fiber, including shape and geometric parameters, is more important. Which directly determines the performance of the fiber, e.g., micron-sized changes in the core diameter of a multicore fiber directly determine the number of modes supported by the fiber.
At present, an optical fiber end face detector is used for detecting the shape of the optical fiber end face, and the optical fiber end face detection device is internally provided with a common microscopic system and is generally used for detecting the end face of a standard single-mode optical fiber, wherein the detection result comprises surface shapes, stains and the like. A disadvantage of such a device or method is that it is not possible to measure the end face morphology and geometrical parameters accurately, especially in case of special optical fiber end faces that are not flat.
Disclosure of Invention
Aiming at the defects in the prior art, the application provides a method and a device for detecting the end face of an optical fiber so as to realize accurate measurement of the end face of the optical fiber.
The first aspect of the present application relates to a technical solution of an optical fiber end face detection method, the method comprising the following steps:
converging incident light from the end face of the optical fiber through at least one lens to image the end face of the optical fiber on an image plane;
acquiring image information of the end face of the optical fiber based on imaging of the image plane, and measuring optical fiber parameters based on the image information;
and blocking part of light rays on an image side focal plane formed by the at least one lens, so that the intersection point position of the object side chief ray in the light path tends to be infinity.
Preferably, a portion of the light is blocked at the image side focal plane of the at least one lens such that incident light parallel to the optical axis is able to radiate to the image plane.
Preferably, the light is selectively blocked by an aperture stop disposed at an image side focal plane of the at least one lens.
Preferably, the at least one lens comprises one or more superlenses;
the superlens includes a substrate, and
the structure units are arranged on the surface of the substrate in an array manner, and each structure unit consists of periodically arranged nano structures;
the super lens is configured to focus incident light at a focal point based on phase distribution of the nanostructures.
Preferably, the at least one lens includes one or more convex lenses.
A second aspect of the present application relates to a technical solution of an optical fiber end face detection apparatus, which includes:
at least one lens for converging incident light from the fiber end face so that the fiber end face can be imaged on an image plane;
the image sensor is arranged on the image surface of the at least one lens and is used for acquiring image information of the end face of the optical fiber according to imaging of the end face of the optical fiber;
and the aperture diaphragm is arranged on the image side focal plane of the at least one lens and is used for blocking part of light rays, so that the intersection point position of the object side chief rays of the lens in the light path tends to be infinity.
Preferably, the at least one lens comprises one or more superlenses;
the superlens includes a substrate, and
the structure units are arranged on the surface of the substrate in an array manner, and each structure unit consists of periodically arranged nano structures;
the super lens is configured to focus incident light at a focal point based on phase distribution of the nanostructures.
Preferably, based on the arrangement of the nanostructures, the optical phase of the superlens satisfies:
wherein, (x, y) is the relative position coordinate of the nanostructure, f is the focal length, and λ is the wavelength of the operating band.
Preferably, the structural units are regular hexagons or squares;
and at least one nanostructure is arranged at each vertex and the center of the regular hexagon, and at least one nanostructure is arranged at each vertex and the center of the square.
Preferably, the at least one lens includes one or more convex lenses.
Preferably, the aperture stop diameter is 18 μm to 23 μm.
Preferably, the at least one lens focal length is 30 μm to 45 μm.
According to the method or the device in the technical scheme, the diaphragm is arranged on the focal plane, so that the light is partially blocked, and the method or the device has the characteristic of an object side telecentric optical system. The imaging of the end face of the optical fiber is not affected by the change of the distance, and the shape and the size of the end face of the optical fiber can be accurately obtained. The method has the advantage of clear edges, so that the edges can be accurately locked, and the geometric parameters of the fiber core can be obtained. The Huygens superlens is further used, so that the scheme also has the advantage of small volume, can realize convenient and rapid measurement, and has the advantage of low cost.
Drawings
FIG. 1 is a graph comparing the inclination of the fiber end face with the detection result of the prior art;
FIG. 2 is a schematic diagram of an optical path for performing non-planar fiber end face detection in the prior art;
FIG. 3 is a schematic view of an optical path according to the technical scheme of the present application;
FIG. 4 is a schematic view of the optical path of the solution of the present application using superlenses;
FIG. 5 is a schematic diagram of a nanostructure;
FIG. 6 shows nanostructure phase and transmittance;
FIG. 7 is a schematic diagram of regular hexagonal and square structural units;
FIG. 8 is an end-face dimension of a seven-core single-mode optical fiber to be tested in accordance with an embodiment;
FIG. 9 is a comparison of the superlens solution of the present application with prior art measurements;
FIG. 10 is a graph of a calculated pattern of the superlens solution of the present application versus the prior art;
fig. 11 is a schematic diagram of a scheme of using a lens set and an optical path thereof in an embodiment of the present application.
The drawing is marked:
1, an optical fiber to be measured, and 11 end faces of the optical fiber to be measured;
2 a lens; a first lens 21; 22 a second lens;
3, an aperture diaphragm; 4 image plane.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the application.
Detailed Description
The present disclosure will be described more fully hereinafter with reference to the accompanying drawings, in which embodiments are shown. The present disclosure may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Like numbers refer to like elements throughout. Also, in the drawings, the thickness, ratio, and size of the parts are exaggerated for clarity of illustration.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, unless the context clearly indicates otherwise, "a," "an," "the," and "at least one" are not meant to limit the amount, but are intended to include both the singular and the plural. For example, unless the context clearly indicates otherwise, the meaning of "a component" is the same as "at least one component". The "at least one" should not be construed as limited to the number "one". "or" means "and/or". The term "and/or" includes any and all combinations of one or more of the associated listed items.
Unless otherwise defined, all terms used herein, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms as defined in commonly used dictionaries should be interpreted as having the same meaning as that of the relevant art context and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
The meaning of "comprising" or "including" indicates a property, quantity, step, operation, component, element, or combination thereof, but does not preclude other properties, quantities, steps, operations, components, elements, or combinations thereof.
Embodiments are described herein with reference to cross-sectional illustrations that are idealized embodiments. Thus, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, embodiments described herein should not be construed as limited to the particular shapes of regions as illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. For example, a region shown or described as being flat may typically have rough and/or nonlinear features. Also, the acute angles shown may be rounded. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the precise shape of a region and are not intended to limit the scope of the claims.
The inventor finds that the prior art cannot accurately measure the shape and geometric parameters of the end face, especially in the case of uneven end face of a special optical fiber. The reason for this is that in general, the cut end faces of the optical fibers cannot be perfectly parallel, and there is always a certain inclination angle. This results in different object distances in the imaging system, so that the imaging size is changed, and deviations from the true result exist, as in fig. 1, for example, a multi-core optical fiber, and it is important how to accurately measure the true shape and size when a certain inclination angle exists on the end face of the optical fiber (the cores of various special optical fibers are not located on one object plane).
In view of the above, in the prior art, an optical path for imaging an end face of an optical fiber is analyzed, as shown in fig. 2, the end face of the optical fiber is divided into three equal-sized areas (the object heights are the same and the object distances are different), and an imaging image of each area is obtained by taking an imaging position of a center object passing through a conventional lens as an imaging plane.
In fig. 2, an image of the lower end is taken as an example, and it can be seen that light is not focused to form a diffuse spot, and thus a blurred image is obtained. The center of the diffuse spot is taken, the image height and the image analogy at the upper end can be obtained. It can be seen that the solution of the conventional lens images blur and the resulting image heights are also each different, since the magnification of the conventional lens varies with the object distance.
In view of the foregoing technical problems, in an embodiment of a first aspect of the present application, a method for detecting an end face of an optical fiber is provided, where the method includes the following steps:
converging incident light from the end face of the optical fiber through a lens or a lens group to enable the end face of the optical fiber to form an image on an image plane;
acquiring image information of the optical fiber end face based on imaging of the optical fiber end face on an image plane, and measuring optical fiber parameters based on the image information;
and blocking part of light rays on the image side focal plane of the lens, so that the intersection point position of the object side chief rays in the light path tends to be infinity, or as much as possible of incident light parallel to the optical axis can reach the image plane, and the entrance pupil tends to be infinity.
The method forms the optical path shown in fig. 3, and the whole constitutes a telecentric optical system. It can be seen that the magnification is substantially unchanged with object distance, and the imaging edges are clear. As can be seen from the figure, on the image plane, three areas are imaged in the image space, and not only the edges are clear, but also the edges are equal in size. This solves the problem of the conventional lens.
The above embodiments are additionally described in terms of various optical devices capable of converging light and imaging the image on an image plane, including, but not limited to, conventional lenses, super surface lenses, huygens principle super lenses, and like monolithic mirrors or mirror sets, systems, and the like, comprising one or more of them. The image information of the end face of the optical fiber is acquired at the image plane, and an image sensor such as CMOS, CCD and the like can be arranged, wherein the image sensor is connected with a data storage device, a display device or a detection analysis device and is used for analyzing and measuring the section of the optical fiber to be measured based on image signals.
In a preferred embodiment, a portion of the light is blocked at the focal point of the lens so that incident light parallel to the optical axis can radiate to the image plane. It should be understood that the above-mentioned "incident light rays parallel to the optical axis" includes incident light rays nearly, nearly parallel to the optical axis, and is not meant to exclude unavoidable, unavoidable manufacturing tolerances, measurement tolerances, and the like in the relevant art.
In a preferred embodiment, the light is partially blocked by a diaphragm arranged at the focal point of the lens. The diaphragm is required to be disposed at the focal plane of the lens. The imaging effect can be adjusted by adjusting the aperture of the diaphragm. Depending on the size of most fiber end faces, the aperture of the stop may be 18 μm, 19 μm, 20 μm, 21 μm, 22 μm, 23 μm, any value in between, etc.
In a preferred embodiment, the focal length of the lens may be selected in the range of 30 μm to 45 μm. By way of example, it may be 30 μm, 32 μm, 35 μm, 40 μm, 44 μm, 45 μm, any value therebetween, or the like.
In a preferred embodiment, a Huygens superlens is chosen as the lens, or alternatively, as one or more lenses in a lens group, such superlens comprising a substrate, and
the structure units are arranged on the surface of the substrate in an array manner, and each structure unit consists of periodically arranged nano structures;
the super lens is configured to focus incident light at a focal point based on phase distribution of the nanostructures.
The supplementary explanation of the above preferred embodiment is: the nanostructures constitute a supersurface on the substrate. The supersurface is a layer of artificial nanostructured film of sub-wavelength that modulates incident light according to the supersurface structural elements thereon. The super-surface structure unit comprises an all-dielectric or plasma nano antenna, and can directly regulate and control the characteristics of light such as phase, amplitude, polarization and the like. In this example, the nanostructure is an all-dielectric structural unit, and has high transmittance in a target band, and when the working band is visible light, the substrate material can be selected from visible light transparent materials such as fused quartz, crown glass, flint glass, sapphire, etc., and the nanostructure can be selected from materials such as silicon nitride, titanium oxide, gallium nitride, gallium phosphide, hydrogenated amorphous silicon, sapphire, silicon oxide, etc.; when the working wave band is far infrared (8-12 μm), the base material can be chalcogenide glass, zinc sulfide, zinc selenide, crystalline germanium, crystalline silicon and other materials, and the nanostructure can be crystalline silicon, crystalline germanium and other materials. When the working wave band is near infrared, the substrate material can be near infrared transparent materials such as fused quartz, crown glass, flint glass, sapphire and the like, and the nanostructure can be materials such as crystalline silicon, amorphous silicon, hydrogenated amorphous silicon and the like.
The nanostructures may be air-filled or other transparent or translucent material in the operating band, and it should be noted that the absolute value of the difference between the refractive index of the material and the refractive index of the nanostructures is greater than or equal to 0.5.
The supplementary explanation of the above preferred embodiment is: the nanostructure comprises a nano cylinder, a nano ring column, a nano round hole, a nano ring hole and the like. The nanostructure unit comprises a substrate and nanostructures on the substrate, wherein the nanostructures can be separated by air or filled with other materials, so that the purpose of protecting the micro-nano structure is achieved. In the design process, the shape and system of the nanostructure can be selected based on the constructed nanostructure database. The selected nanostructure not only requires high transmittance in the operating band, but also satisfies the phase full coverage of 0 to 2pi, as shown in fig. 6.
In a preferred embodiment, based on the arrangement of the nanostructures, the optical phase of the lens satisfies:
wherein, (x, y) is the relative position coordinate of the nanostructure, f is the focal length, and λ is the wavelength of the operating band. Further, based on the above requirement of optical phase, the nanostructure can be further designed and optimized, according to the phase of the nanostructure required by different wavelengths, the nanostructure with the closest phase is searched in the nanostructure database, and the nanostructure is searched for an optimization algorithm capable of minimizing the weighting error, and the principle of the optimization algorithm can be represented by the following formula:
where delta (x, y) is the total error at the subsurface coordinates (x, y), phi (x, y, lambda) is the theoretical phase at wavelength lambda,an actual phase at wavelength λ for the j-th structure in the database, and c i For the weight coefficient of this wavelength, the weight is typically 1. By searching through the database, the structure that minimizes the total error Δ is found to be placed at the hypersurface (x, y) location.
In a preferred embodiment, the lens is a convex lens, that is, a conventional lens plus aperture stop solution.
It should be appreciated that the main technical effects of the present application can be achieved using either conventional lenses or superlenses. The super lens scheme is selected, so that the super lens has the advantages of light weight, thinness, simplicity and low cost, and can realize more complex functions according to the phase design of the super surface structure. Because of its compatibility with the semiconductor manufacturing process, it has the potential to wafer level package with image sensors.
An embodiment of the second aspect of the present disclosure is an optical fiber end face detection device for detecting an optical fiber end face by the above-mentioned test method, as shown in fig. 3 or fig. 4, including:
a lens 2 or a lens group for converging incident light from the fiber end face 11 so that the fiber end face 11 can image on the image plane 4;
the image sensor is arranged on the image surface 4 of the lens and is used for acquiring image information of the optical fiber end face according to imaging of the optical fiber end face 11;
and the aperture diaphragm 3 is arranged on the image side focal plane of the lens and is used for blocking part of light rays, so that the intersection point position of the object side chief ray of the lens in the light path tends to be infinity.
In a preferred embodiment, the lens is a superlens, or a superlens is included in a lens group, the superlens comprising a substrate, and
the structure units are arranged on the surface of the substrate in an array manner, and each structure unit consists of periodically arranged nano structures;
the super lens is configured to focus incident light at a focal point based on phase distribution of the nanostructures.
In a preferred embodiment, based on the arrangement of the nanostructures, the optical phase of the superlens satisfies:
wherein, (x, y) is the relative position coordinate of the nanostructure, f is the focal length, and λ is the wavelength of the operating band.
In a preferred embodiment, the structural units are regular hexagons or squares;
and at least one nanostructure is arranged at each vertex and the center of the regular hexagon, and at least one nanostructure is arranged at each vertex and the center of the square.
Supplementary explanation of the above preferred embodiment: the structural unit is a regular hexagon, and at least one nanostructure is arranged at each vertex and the center of the regular hexagon. Alternatively, the structural unit is square, and at least one nanostructure is arranged at each vertex and center position of the square. In an ideal state, the structural units should be nano structures arranged at the fixed points and the centers of hexagons or nano structures arranged at the fixed points and the centers of squares, and it should be understood that the actual product may have the defect of nano structures at the edges of the superlens due to the limitation of the shape of the superlens, so that the superlens does not meet the requirement of complete hexagons/squares. Specifically, as shown in fig. 7, the structural units are formed by regularly arranging nano structures, and a plurality of structural units are arranged in an array to form a super-surface structure.
One embodiment, as shown on the left side of fig. 7, includes a central nanostructure surrounded by 6 peripheral nanostructures equidistant therefrom, each of which is circumferentially uniform to form a regular hexagon, which can also be understood as a combination of regular triangles of nanostructures.
One embodiment, as shown on the right side of fig. 7, is a central nanostructure surrounded by 4 peripheral nanostructures equidistant therefrom, forming a square.
In a preferred embodiment, the lens is a convex lens, or at least one convex lens is included in the lens group.
In a preferred embodiment, the aperture of the diaphragm may be 18 μm, 19 μm, 20 μm, 21 μm, 22 μm, 23 μm, any value in between, etc. The focal length of the lens may be selected in the range of 30 μm to 45 μm. By way of example, it may be 30 μm, 32 μm, 35 μm, 40 μm, 44 μm, 45 μm, any value therebetween, or the like.
In an embodiment of the third aspect of the present application, measurement of a seven-core single mode optical fiber as shown in fig. 8 is involved. As shown in the figure, the diameter of the cladding of the optical fiber to be measured is 125 mu m, each fiber core is equal in size, the diameter is 12 mu m, the core spacing is 40 mu m, and only a single mode can be supported by each core through calculation. Such optical fibers are used in high capacity optical fiber communication systems.
In this embodiment, a huygens superlens scheme is used. The design wavelength of the super lens is 1550nm, the diameter of the super lens is 150 mu m, the super lens is slightly larger than the diameter of the cladding, and the focal length of the super lens is 50 mu m. The superlens is a general convergent superlens, the base material is fused quartz, the micro-nano structure material is silicon, the type of the micro-nano structure is a cylinder, the height of the cylinder is 1000nm, and the period is 800nm. The object distance l1 in the system is defined as the distance from the intermediate core to the superlens, set to 500 μm and the diameter of the aperture stop to 20 μm. The inclined angle of the end face of the seven-core optical fiber is 60 degrees (the included angle between the inclined plane and the optical fiber direction), and the image plane distance is 650 mu m. The parameters of the end face of the fiber were finally obtained by huyghen superlens imaging as shown in fig. 9. The cores were almost equally large and sharp-edged, with a diameter of 12.4 μm.
It can also be seen from the lower half of fig. 9 that the object distance image distance parameters are the same by conventional lens imaging, and the measured fiber parameters are shown in fig. 9. It can be seen that the imaged edges are not sharp and are not equal in size, resulting in a diameter of the underlying core of 14.5 μm. And for the fiber core diameter obtained by measuring the two schemes, combining the refractive index parameters of the materials, the mode which can be supported by the optical fiber can be obtained. As can be seen from the calculation result, the core obtained by the huyghen superlens method can support the LP01 mode, which is the same as the design scheme and supports only single-mode transmission. The core parameters obtained by the conventional lens, which can support the LP11 mode in addition to the LP01 mode, are contrary to the design. Thus, it is possible to obtain a more accurate shape and size of the fiber end face using the huygens superlens scheme.
Fig. 11 also shows an embodiment of a lens group using multiple lenses. Illustratively, a first lens 21 and a second lens 22 are included, one on each side of the aperture stop 3. Preferably, the first lens 21 and/or the second lens 22 are optical devices composed of superlenses. The embodiment has the advantages that the telecentric effect is better than that of a single lens, the imaging edge is clearer, and the object distance allowable range under the same magnification is large.
In the above embodiment, the characteristics of the object-side telecentric optical system are utilized: the vertical magnification is independent of the object distance. Therefore, the geometrical parameters of the fiber core can be accurately measured under the condition of the non-planar fiber end face, and the problem of error does not occur. Meanwhile, the object space telecentric optical system has the advantage of clear edge, so that the edge can be accurately locked, and the geometrical parameters of the fiber core can be obtained. The scheme also has the advantage of small volume, can realize convenient and quick measurement, and has the advantage of low cost.
The above embodiments are only for illustrating the technical solution of the present application, and are not limiting thereof; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims (10)
1. A method of fiber-optic endface detection, comprising:
converging incident light from the end face of the optical fiber through at least one lens to image the end face of the optical fiber on an image plane;
acquiring image information of the end face of the optical fiber based on imaging of the image plane, and measuring optical fiber parameters based on the image information;
wherein, blocking part of light at the focal plane of the image side of the at least one lens, so that the intersection point of the principal ray in the optical path at the object side tends to be infinity;
the at least one lens comprises one or more superlenses;
the superlens includes a substrate, and
the structure units are arranged on the surface of the substrate in an array manner, and each structure unit consists of periodically arranged nano structures;
the super lens meets the requirement of optical phase based on the arrangement of the nano structure, and the nano structure is searched in a nano structure database according to the phase required by the super lens under different wavelengths.
2. The method of claim 1, wherein blocking a portion of the light at the focal plane of the at least one lens at the image side allows incident light parallel to the optical axis to radiate to the image plane.
3. The fiber-optic endface detection method of claim 1 or 2, wherein blocking a portion of light at an image-side focal plane of the at least one lens is performed by means of an aperture stop.
4. The method of claim 1, wherein the at least one lens comprises one or more convex lenses.
5. An optical fiber end face detection device, comprising:
at least one lens for converging incident light from the fiber end face so that the fiber end face can be imaged on an image plane; the image sensor is arranged on the image surface of the at least one lens and is used for acquiring image information of the end face of the optical fiber according to imaging of the end face of the optical fiber;
the aperture diaphragm is arranged on the image side focal plane of the at least one lens and is used for blocking part of light rays, so that the intersection point position of the object side chief rays of the lens in the light path tends to be infinity;
the at least one lens comprises one or more superlenses;
the superlens includes a substrate, and
the structure units are arranged on the surface of the substrate in an array manner, and each structure unit consists of periodically arranged nano structures;
the super lens meets the requirement of optical phase based on the arrangement of the nano structure, and the nano structure is searched in a nano structure database according to the phase required by the super lens under different wavelengths.
6. The fiber-optic endface detection apparatus of claim 5, wherein, based on the arrangement of nanostructures, the optical phase of the superlens satisfies:
wherein, (x, y) is the relative position coordinate of the nanostructure, f is the focal length, and λ is the wavelength of the operating band.
7. The fiber-optic endface detection apparatus of claim 5, wherein the structural elements are regular hexagons or squares;
and at least one nanostructure is arranged at each vertex and the center of the regular hexagon, and at least one nanostructure is arranged at each vertex and the center of the square.
8. The fiber-optic endface detection apparatus of claim 5, wherein the at least one lens includes one or more convex lenses therein.
9. The fiber-optic endface detection apparatus of claim 5, wherein the aperture stop diameter is 18 μm to 23 μm.
10. The fiber-optic endface detection apparatus of claim 5, wherein the at least one lens has a focal length of 30 μιη to 45 μιη.
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